Recommended for following cartridges TM 7U Ortofon OM Stylus History Chart Below is a chart that denotes which styli were sold with which cartridges, past and present. However, keep in mind that all these styli are interchangeable. For expamle, if you have an old Ortofon TM 7U cartridge, you can order a 20 or 30 stylus if you're interested in upgrading. There are differences in the respective anatomies of these cartridges, but upgrading the stylus will yield better results regardless. Details on Ortofon Cartridge and Stylus Installation and Maintenance